Enciphering and deciphering device for secret telegraph systems



April 18, 1950 w. M. BAcoN ENCIPHERING AND DECIPHERING DEVICE FoR SECRET TELEGRAPH SYSTEMS Filed Dec. 3, 1946 5 Sheets-Sheet l rlnw 3 f5 L /NVEA/TOR W M @ACQ/V A TTOR/VEV April 18, 1950 Filed Das. s, 1946 w. M. BACON 2,504,621 ENCIPHERING AND DECIPHERING DEVICE FOR SECRET TELEGRAPH SYSTEMS 5 SheetshSheet 2 KEYBOARD ATTORNEY April 18, 1950 w. M. BACON ENCIPHERING AND DECIPHERING DEvIcE EoR SECRET TErEGREPH-SYSTEMS 5 Sheets-Sheet 3 Filed Deo. 3. 1946 April 18, 1950 w. M. BAcoN ENCIPHERING AND DECIPHERING DEVICE FOR SECRET TELEGRAPH SYSTEMS 5 Sheets-Sheet 4 Filed Dec. 3, 1948 WOR llll Ile nf 3.3m ...b Ehud@ PS nit wmom .31; #E A a W M. BA CON A 7' TURA/EV April 18, 1950 w. M. BACON' ENCIPHERING AND .DECIPHERING DEVICE FOR SECRET TELEGRABH SYSTEMS Filed Dec.

s shane-snaai v5,

J lle ILLIIQ .shut

/N VEN TOR W M. BA CON A TTORNEV Patented Apr. 18, 1950 F ENCIPHERING AND DECIPHERING DEVICE FOR SECRET TELEGRAPH SYSTEMS Walter M. Bacon, New York, N. Y., assignor to Bell Telephone Laboratories, Incorporated, New York, N. Y., a corporation of New York Application December 3, 1946, Serial No. 713,651

10 Claims. l

This invention relates t secret telegraph systems and more particularly to an enciphering and deciphering device adapted for use in such secret telegraphic systems.

In telegraph systems, messages are transmitted and received in any well-known code, and if intercepted in this condition, during the course of transmission, they are intelligible to any one familiar with the code. However, in secret telegraph systems the message signals are altered before transmission over the lin-e, and when intercepted in their altered form are unintelligible. At the transmitting end of a Secret system, the intelligible messages prepared at the transmitter are, before being impressed on the line, enciphered by means of other signals of what is generally known as a key code, and the enciphered messages with their altered signals are transmitted over a line so that any interception on the line will cause to be received by the interceptor unintelligible messages. At the nal receiving end, these unintelligible messages are deciphered by means of other signals identical with those of the key code at the transmitting end, and the deciphered messages are recorded to produce the messages as originally prepared.

Heretofore in secret telegraph systems difficulties were experienced in developing a completely shielded device for transmitting messages to the enciphering set or for receiving messages from the deciphering set for recordation.

At the sending end where the transmitting device may be a keyboard or an automatic tape transmitter or a transmitting relay of a sending teletypewriter, or at the receiving end where the receiving device may be a line relay or a repeating relay or the selector magnet of a receiving teletypewriter, it has been found that each device, upon the make or break of its operating contacts radiates a short, sharp Yvoltage pulse. These pulses when radiated in a location which is comparatively free from other electrical disturbances and in which a ciphering or deciphering set is operated, mayA be surreptitiously or otherwise received, or picked-up, by a radio receiving device located in an adjacent room or within some other short distance or at a much greater distance along a power or signal wire which is connected to or passes closeby the receiving set, and are recorded as pulses by an oscillograph. From these pulses appearing on an oscillogram may be constructed the signals of the complete message as originally prepared,

An object of the present Ainvention is to cipher and decipher messages through a single rotary distributor of special type cooperating with two tape sensing mechanisms.

Considerable work has been done on secret telegraph systems to prevent the radiation from the plain text signal impulses of voltage pulses that may be picked-up and read at a distance by means of radio receivers. While successful radiation prevention methods have been developed, the problems involved are complex and there is no assurance that radiation will not take place when the equipments are in use in the field as the doors may not be tightly closed or all the shields may not be properly installed due to carelessness on the part of the operator.

According to the present invention there is provided a room circuit device adapting a single code tape for use in telegraph cipher systems for preventing an intelligible pick-up, by means of a radio receiver, of voltage pulses radiated by a teletypewriter transmitter or receiver during the process of preparing a perforated record of an enciphered message for future reference or future transmission over an outgoing line, or a printed record of a deciphered message. The room circuit device is further adapted to prepare by means of a special keyboard a printed or perforated plain text message, or both, for future enciphering. The method of transmitting directly from a special keyboard directly to an outgoing line is described in Bacons copending application, Serial No. 653,256, filed March 9, 1946, which issued as Patent No. 2,463,236 on March 1, 1949.

The enciphering operation may be divided into two parts, which consist of (1) perforating a tape with plain text message signals, and (2) -enciphering the message so perforated on the plain text tape by mixing, or interacting, it with a key code perforated on a second tape, by means of a single rotary distributor of a special type, whereby a new combination of the two, that is, the message code and the key code, is impressed on a typing reperforator to perforate on a third tape such combination as an enciphered message. The deciphering operation may also be divided in two parts which consist of (l) placing a tape containing an enciphered perforated message on the sensing pins of a transmitter, and (2) placing the tape containing the perforated key code on the sensing pins o f a second transmitter, the transmitters respectively transmitting the enciphered message code and the key code simultaneously through the single rotary distributor of special type to impress it on a teletypewriter wherein the Original plain text message is recorded. The distributor of special type comprises two segmented rings interconnected by a brush for effecting the interaction oi two codes transmitted from two tape sensing mechanisms.

A main feature of the invention is the provision of a compact telegraphic transmitting and receiving de-vice for-enciph-ering and deciphering messages `for secret communication, comprising two automatic tape sensing mechanisms, or transmitters, simultaneously operating in conjunction with the rotary distributorV o specialV type and telegraphic receiving apparatus equipped with dummy circuits identical with the regular-selector circuits whereby voitage plllSesfradiated .by .plain text signals are masked bytotherapulses radiated i by the dummy circuits to prevent detection or a communication.

The invention will be better understood by reference to the following detailed description taken in connection 'avith the accompanying drawings in` which:

Fig. 1 shows a telegraphic .transmitting .and receiving device comprising -two automatic tape transmitters operating .in .conjunction with the rotary distributor of special .type to record at a typing vreperforaltor adeciphered messageand at a -reper-forator an enciphered message;

Fig. 2.showsv ,aspecialkeylooard which is preieraloly .arranged for .use `with .the `teletypewriter shown .in Eig. v1, when .itis desired to prepare either a .printed or v.perforated plain text message, Aor both;

Fig. B shows vin .tabulated form the products obtained when Ythe marking and spacing impulses of a lcharacter-of .a key code are superimposed on the -marking'and spacing impulses of a character -of a -deciphered or plain text, message 'and an enciphered message;

Eig. Ll shows a schematic circuit layout vfor the apparatus shown in.-Fig-s. 1 and 2, `wherein the single distributor vis shown developed to furnish a clearer view of the various circuit paths provided for the enciphering andthe :deciphering operations;

lFig. 5-.is ag-diagrammatic showing vof a signal wave Vand .the vvoltage fpulse pick-up waves. `inwolved in the renciphering process; and

Eig. 6yi's -a diagrammatic showingof YaLsignal wave Yand the voitage pulse pick-up waves involved in the deciphering process.

All the apparatus 'for ztheftransmitting and receiving equipment shown in .'Figs. 1 and i2 lis preferably arranged in one room wherein it is desired `to u'ecordl enciphered kand'deciiphered imessages, both outgoing andzincoming, .prepare plain text -messages :for 4reference vpurposes or .for 'future transmission through. an enciphering 'device as .enciphered lmessages to an .outgoing line.

The signal Ycode used :herein for both message .signals zand ,key code signals iis the :start-stop,

five-.unit permutation lcode which .comprises five selectin-g `pulses' used -inivarious .combinations `rof fcurren and "no current intervals, namely, mark and "fspacef dependingupcn the signal transmitted, Aeach 'group of five 'selecting pulses The use of reference characters has been kept to a denite plan. Thus all numerals in each of the figures are prexed by a digit indicating the gure in which the element is located, ior example, all reference characters in Fig. 1 are numerals between 100 and 199, the hundred nu- Aineral .designating the figure. Like parts have fcorieslponding referencev .characters except for the hundred numerals.

Referring to Fig. 1, automatic tape transmitter lill is arranged to receive tape i252 perforated ivithxavmessage from unit HB3 which may be a separate keyboard perforator, a typing reperfo- .ratoriadaptedtofreceive from another line a mes- Sage in vpiain textzor an enciphered message, or

a 'tape guide for perforated tape either in an unbrokenlength or, consisting of several pieces spliced together, containing a plain text message or fan .enciphered message. Preferably unit W3 receives perforated tape previously prepared for transmission. Automatic tape transmitter ltd is arranged to receive perforated tape |65 from unit l-,id 4.which serives as 4a guide lfor tape 05 perforated with signals of the key code. Each signal of: the key code on tape 1,95 is impressed through contacts I-. `on @the segments of 'the inner ring 'litt to be :superimposed cna signal simultaneously impressed 'on :the segments vci? outerring IES ofthe 'transmitter-distributor according to thepresent invention, through transmitting contacts led by -tape fill?.

When tape 92 is perforated y:with signals corresponding to the plaintext message the superimaposition of the signals -iof the key -code apro duces Vatreperiorator .it an enciphered message prepared .for delivery or storing pui-poses, or transmission over another .line iciicuit, but when tape ll contains an enciphered message then the superimposition of its signals on the signals of vthe 'key code produces aY deciphered message at a .printing Vteletypewriter such as diagrammatically :shown in .box H9.

Fig. 3. shows iin tabulated fformfthe changes eected in the selecting impulses of a signal character .representing the letter AI vwhen such signal impulses are generated `simultaneously with the selecting innpulsesof a signal combina- 'tionfo'fv a key code. The simultaneous genera.- tionof two characterscauses 'the signal combination .of fone character to be superimposed on the signal combination of the other characte so -thatfa' different productis transmitted instead 'of the signal combination -oi either or both they :characters originally prepared. For example, should a selecting impulse which is a mark Vin a signal combination in A'key code perlforate'dinftape H15 to'besuper'imposed on a selecting impulse `which -is also a mark in signal combination vperforated in message tape H52 which message maybe `infi'olain 'text form or envkciphered, the product will be va mark. Should 'the corresponding selecting impulses on the 'two tapes vbe spacing the product would be o. mark. However, should :the corresponding se- 'lec'ting'pulses bediiierent, :that is, one marking and the 'other spacing, the 'product will be a space, In other words, vimpulses of like nature Awhen superimposed on each other produce a marking impulse-and'impulsesof unlike nature when superimposed on each other produce a spacingimpulse. In Fig; B'under Encipherine are shown the selecting'impulses-of vthe letter I to be space, mark, mark, space and space andthe 'correspondingcselecting impulses o'f a character, such :as `letter fZ;-iin 'fthe ,key .code .are imark,

.teletypewriter H0. `ordinary keyboard such as shown in the disclo- .sure of Morton Patent Re. 20,330, supra.

space, space, space and mark representative of the code that is to be superimposed on the code for the letter I. The product resulting from this superimposition and prepared to be transmitted, instead of the signal combination representative of letter I or letter Z, is constituted of the following selecting impulses: space, space, space, mark and space. Under Deciphering the same rule applies, except that the superimposition operates in the reverse order. For example, the same signal combination, such as that for letter Z, of the key code is superimposed, but in this case the superimposition is on a signal comb-ination comprising the following selecting impulses: space, space, space, mark and space, which are the same as those contained in the product obtained in the enciphering operation. The product obtained in the deciphering operation comprises space, mark, mark, space and space which together with the regular start and stop impulses constitute the signal combination of letter 1, the letter produced in the deciphered message.

The apparatus employed in Figs. 1 and 2 may be of the types disclosed in the United States patents hereinafter referred to:

Transmitting units respectively comprising transmittingcontacts I0! arranged to be controlled by perforated tape |02 and transmitting contacts it arranged to be controlled by tape |05, and associated with transmitter distributor Y35, are, with certain modications as shown and as will be hereinafter described, of the type disn closed in United States Patents 2,055,567 and 2,252,014, respectively granted to E. F. Watson on September 29, 1936, and W. Y. Lang on November l1, 1941.

Reperforator m9 may be of the typing reperforator type disclosed in United States Patent 2,255,794, granted to R. A. Lake on September 16, 1941, but modified as hereinafter described.

Teletypewriter lll! is preferably of the keyboard perforator-transmitter-printer type comprising a printing teletypewriter combined with keyboard perforator and transmitter preferably of the type disclosed in United States Patent 1,965,602, granted to R. A. Lake on July 10, 1934,

but modified as hereinafter described.

The above-mentioned patents show in detail the transmitting, the selecting, the printing and the perforating mechanism for use with teletypewriter signaling, and therefore these patents are hereby made a part of this application as if fully set forth herein.

Switch il is provided for changing the device, or arrangement, from enciphering operation to deciphering operation and vice versa. The switch when operated toward the right sets the `device in condition for enciphering the plain text message signals with the key code signals whereby the record produced is unintelligible. The switch when operated toward the left sets the ar- :rangement in condition for deciphering an unintelligible enciphered record by means of the key code to produce the original plain text message signals from which an intelligible record is 0btained The special keyboard transmitter arrangement shown in Fig. 2 and disclosed in -Bacons copending application, Serial No.653,256, supra, is arranged for connection through switch l!! to teletypewriter H0. This special keyboard together with its tape perforator may be part of It is a modication ofthe Circuit changes as shown in the apparatus for both reperforator |09 and teletypewriter |||l are required when they are used with the arrangement shown in Fig. 1. The receiving side of each apparatus is changed in that the line relay is operated on a polar basis and the product of this relay is sent either to the printer selector magnet or to a dummy magnet in an operating circuit which has an impedance equal to that of the operating circuit for the printer selector magnet.

The operating circuit of the selector magnet and the dummy magnet in each of reperforator |139 and teletypewriter |10 includes two parallel paths for respectively operating the selector and the dummy magnet of its own machine. The two parallel paths at each machine have a common path extending through the lower winding of its line relay so that the operating current for either of its two magnets is utilized for holding its line relay in the position to which the relay was last operated by the operating current in the upper winding of the relay. The resistors in the paths for operating the magnets are of low, but equal, resistance values and the resistors in the common path are of considerably higher, but also equal, resistance values. The current permitted to now through the lower winding of each line relay will be just sufficient to hold the line relay in the position to which it was last operated providing there is no current flowing in the upper winding of the relay at the time. Accordingly, in reperforator E99, resistors and |46 are of con-V siderably higher resistance Values than those of resistors M3 and |41 and in teletypewriter H9, resistors it! and |62 are of considerably higher resistance values than those of resistors |59 and The special transmitter-distributor, during each revolution of its rotatable brush arm |34 interconnects, in turn, the corresponding sensing contacts of the two sensing mechanisms represented by transmitting contact sets |0| and |84 whereby grounded negative battery |64 and grounded positive battery furnish current for operating the line relays of machines |09 and i l@ in accordance with the polarity of each oi the selecting impulses of the signal combination resulting from combining the corresponding selecting impulses of the two signal combinations simultaneously supplied from transmitting contact sets |0| and its. The sensing contacts are shown as transfer elements represented by armatures Nos. l to 5 in each of sets |0| and |04 and each of these elements of each of sets iti and S94 engages one or the other of its marking (M) and spacing (S) contacts depending on whether or not a perforation in its transmitting tape appears at such point of engagement at the time a signaling combination is being impressed on the distributor ring, the signal combinations in tape |02 being impressed on ring |08 and those in tape |05 being impressed on ring lB'l. Each of the two segmented rings |01 and lilB of the face of the special distributor contains a rest segment, a start segment, a stop segment and ve pairs of segments. One segment of each pair on one ring when connected to its corresponding segment of a pair on the other ring, by the rotating brushes, serves to transmit a selecting impulse for operating the line relay in one or the other of machines |09 and l0', and the other segment oi each pair when connected to its corresponding segment of the pair on the other ring serves to transmit current for operating the selector magnet or the dummy magnet depending on the position to which the associated linereia-y is operated, fllhe current serving to operate the magnets ris also utilized 'to hold :the line relay `operated until the next selecting impulse is received. In ring '|l the'stop segment is connected -trl-'grounded negative battery |39, the vrestsegment, the start segment and segments 1A, 2A, 13A, :4A .and 5e are conneeted to grounded positive battery |55 and segments Nos. i to 5 are respectively connectedto armatures Nos. i to 5 of transmitting contact set |54. In ring l eil the st op andthe Astartsegments are connected `to conduotor 443, the rest segment and segments Nos. 1A, 2A, 3,A 4A and v 5A are connected Yto conductor istanti segmentsNos. 1 to 5- are respectively connected to armatures 1 to 5.of transmitting contact-set llill. Segments Nos, l'to 5 on rings Hl'iand Al e3 serve to complete the circuitsrover which the vfive selecting impulses :of a signal combination are SllCQessivelytransmitted to operate aline relay, and segments Nos. 1A,

2A, 3A, 4A and 5A on the samerings serve to corn- `pletecircuits fortransmitting current foro perating the selector magnet and theidummy .magnet in machines i199 and lill.

All segments of ring iareradially 4arranged ed positive battery |35, Vthe rest segments intern Aconnected bythe brushes and rotatable arrn 1314, conductor |36, thence over two parallel `paths. 'Either of these pathsvmaybeselectedior use-'by operating switch to the position desired,

'When switch-il l is-operated to its-left-'hand position, the path selected is thatwhieh-extends over the left-hand contact and spring No. 1 of switch l l l, conductor lill, armature and marking .contacts of polarized line re1 ay 31S, through the windving of selector ma-griet U32, resistor M3 .of vlow resistance value, to grounded negative battery .1114 whereby `selector nmagnet 142 is `normally held in its operated position. "When switch Ui is operated lto its right-hand `posi-tion, the path selected is that which extends from grounded positive battery 22S (Fig. 2) ,conductor iterminal '235 normally in engagement :with .Contact spring member 23d, conductors. 245 Aand '2M'. right-hand `Contact and spring No. '5 :of switch l i l, conductor l ilgthrough the Winding of selec- W ith SW1-toni L! in its ,rightfhand position, grounded positive v:batte-ivy |35 sube maintaining selector .magnet M2 operated, at

A in ga extend-ing .overthe rest seg'- ments normally engaged `by the brushes on arm i conductori se,-righthand contact .and-spring No. l of switch-l l i, conductor ':|ti!,;arma:ture and marking contact of line relay |338, .through vthe winding of Aselector magnet ilresistor '|43 l,of :low resistance value, -to .f gronnd vpositive :iba-ttor-y When switch is :in tSlet-ha-nd ing Circuit iorselector magneti l2 also flows 'much lesser degree 'through a paralleloath extending over resistor m5 `-ojf high resistance vvalue,

relay 53s, another high'resista'nce resistor i655, `resistor le? of'low resistancevame lio-grounded .negati-ve battery i144. This lesser cust-rent flowtliroughthe xlower winding of' relay |38 `maintion eurineithenonnal. or idle, periods oi trains reperiorator l 09 inasmuch es the .crcuitsltsndr ine `tlinuish the upper Winding o f relay |38 is at this :time Openedlbv the brushesonarm ,|34 of the double .distributor resting onthe rest segments of rings |01 and |08. Likewise, when switch is in its rightehand position the .current owinig through rthe operating circuit -for selector magnet .l 53, a current also flows, butin amuchlesser degree, Athrough a lparallel p ath extending .over resistor |67! of high resistance value, through the 1oWer, or holding, winding of line relay ,13.1, resis-v tor yH52 of high `resistance value, resistor |53 of 10W resistance value, togroundednegative battery tlbandrelay k|31 is thereby normally maintained in its marking position under similar Conditions.

METHOD OF OPERATION Operation of preparing a plaintext message from the special keyboard To prepare a plain text message at :the special Keyboard shown in Fig. 2V and record it either in, printed or perforated vform, 0r -both, at teletypewriter lie, switch is operated to its enciphering, or right-hand, position wherein-the keyboard is connecterl by means of conductors'ZA and-221 to the Winding or" selector magnet |53 and the vinding of dummy magnet Y|54 of teletypewriter HB as shown. For a detailed description of the operation or" the special keyboard and the consequent operation of selector magnet 453 and dummy magnet i511, -wlierebythe dumm-ymagnet, upon operating, serves to mask-pick-up signals radiated ley-the opera-tion of 'the selector mag-net, reference may behad to Bacons copending application, Serial l.\o.lfi 5r3,25.6, Supra, In the copends ing application relays 121 and 122, respectively, correspond to magnets |53 and |54 of the present appli-cation.

However, a brief description of the .Operation of the special keyboard shown in Fig. 2 Will be given `herein.

After a check-up, to see that `tape-stop switch f-l |13 is open and .control switch is closed in its right-hand position, the keys of the special keyboard mayfbe operated. Forexample, should a key, such as keyzii representing theV letter I on the keyboardfbeoperated. momentarily, .key lever .201e-i wouldtbe momentarlyldepressed against `=the tension of .spring member 202 vto -move selector, or code,bars 2HE-f2 and 2|.6 toward fthe left, and selector bars 2.|:5.-.|, 421d-'ll and 2|.S-r-- toward 4the right unless these bars are already in their respective desired positions. The

Y si selector bars 2id-rl, EPG-4, and 21e- 5, upon stituted 'for `grouinied battery :i853 for norma-lis rmoving toward the rig-ht, cause their respectively associated contact spring members 2|8, such as members :ZIB-xl, Et-xd and 248-75 to engage Aspace Iterminals y2 lsf-5|, 2 Q -fs and 2 9.5, re-

specti-vel-y. 'Ihese'lecitor bars :2 Iii-'2 and HIE-3,

lupon moving toward the left, cause their respectively Aassociated spring contact members 'ZIB-f2 and lZIB-.+3 .-.to engage their .mark -terminals ifilati-.e2 andf'ZZe, respectively. 'The depression e .ofkeyleverZJi--I or'an yother -ke lever Vof the ipositioirgthe current flowing-through the onoratn J y keyhoardfcauses universal bar 2| 2 :torotate vin `a.=counter..cloclevvise direction around pin 2 I3 and :the free .end ofthe universal bar moves upwardly yagainst theitension of `coil spring "2M to cause iatch member 2te to disengage throw-out cam i211. Whenlatchmember lfmoves out of en- Vgagement with throw-out cam MJ,r driven clutch :member :297 permitted :to mesh with driving clutch memberfZB :and cam shaft 2,36 starts ro.-

.tains relay lin-its marlsinsror rishtfnandmositatine throngnone revolution, forscycle. should there be no further operation of the keyboard following the operation of the key 200 latch member 2 u having immediately returned to normal under the influence of coil spring 2 l il', would engage throw-out cam 2H at the end of the cycle of cam shaft 295 and the cam shaft would again be locked in its normal position, selector magnet |53 would be maintained operated in its marking position and dummy magnet l5@ would be maintained released in its spacing position. Each of contact spring members Zit remains in engagement with its space terminal 2|9 or its mark terminal 220 to condition a signaling path for transmitting a selecting impulse oi a permutation code signal to either dummy magnet l5# or selector |53, depending on whether such impulse is a space or a mark. These contact spring members remain in engagement with their respective terminals during the rotation of cam shaft 296 and until another key, such as key 200, is momentarily depressed to give the code bars another setting. The contact spring members 2|S are of the transfer contact type so that when a key is depressed causing the selection for the signal combination to be established these keyboard transfer contacts, or elements, will-immediately assume either their spacing or marking positions, depending on the character to 'be transmitted. These transfer contacts are so arranged that they neither make or break the transmission current circuit to cause the transmission of the text signal current impulses and therefore do not cause to be radiated the consequent voltage impulses. However, in order to complete transmission of the signal combinatating through one revolution the transmission current circuit breaks and "makes before and after each of the selecting impulses of the signal combination, the nature of each impulse transmitted depending on whether its corresponding transfer contact is in engagement with itsA marking terminal 220 or its spacing terminal 2|9. In other words, in transmitting the start-stop, five selecting unit permutation code signal, the space and the mark selecting pulses of each signal combination are :rst conditionally established by the simultaneous operation of code bars 2 IS- to 2 |5-5 and their respectively associated Contact spring members ZIB-I to ZIB-5 and then individually transmitted -by the subsequent operation of each of the contact spring members 203-! to 263-5, in turn, during a revolution of shaft 2%. In general teletypewriter practice, the start and the ve selecting impulses are of unit length in duration and the stop impulse is 1.42 times longer. However, in the applicants arrangement the selecting impulses are shortened ten per cent as will be hereinaiter described. There are in all, during a revolution of'cam shaft 206, seven consecutive intervals of operations. Normally selector magnet S53 -is operated in a"'c.ircuit traceable from grounded positive battery` 22S, ccnductor '223, terminal 235 in engagement with contact spring member 235, conductors 245 and 245', right-hand contact and spring memberv No. 5 of switch' l l l, conductor |11, through the winding of selector magnet |53, resistor'flll of low resistance value, to grounded negative battery les. l

The operation resulting from the 'momentary depression of key 200 which is assumed herein to cause the signal combination for letter I to be transmitted, may be described in the following manner: e

(l) At the beginning of the start impulse, or first interval, the contact between contact spring member 234 and terminal member 235 is opened and remains open for the duration of the ve selecting impulses of the signal combination and a start, or space, impulse is thereby sent to the operating circuit for selector magnet |53. Selector magnet |53 being normally energized, releases in response to the space impulse. The opening of the contacts between spring contact member 234 and terminal member 235 is due to the removal of the restraint of switch-shifter 233 when the stop segment of start-stop cam 209 leaves the peak portion 236 of shifter 233 and the start, or rst interval, sector together with the sectors corresponding te the ve selecting impulses, of the cam being of reduced diameter, engage the peak portion 23S. The dummy magnet |54 which is normally in a released condition remains in a released condition for the duration of the rst interval but not necessarily for the duration of the intervals corresponding to the five selecting impulses.

' (2) At the end of the start impulse, peak portion 232-I of switch-shifter 23|J-I continues in engagement with the periphery of normal diameter of cam 2Ei5-I for a short angular distance, say about ve per cent of the unit impulse length o1 the lirst selecting impulse in the second interval, and then engages the indentation on cam 205-i to remove the restraint of switchshifter 23e-l whereby the contact between contact spring Ymember 203-! and terminal 20G-I is permitted to close. This contact remains closed until peak portion 232-I reaches the end of the indentation, which is a short angular distance, say another :tive per cent, before the end of the second interval, that is, the first selecting pulse for the letter I set up at the keyboard has a duration of about per cent of the unit impulse length. The shortened pulse is transmitted in a circuit extending from grounded positive battery 223, contactl spring member 203-l, terminal 20d-l, conductor 223-l, contact spring member 2|8-l and space terminal 2|9-l, conductor 221, right-hand contact and spring No. 4 of switch I conductor |76, through the winding of dummy magnet |54, to grounded negative battery i60. Dummy magnet |54 operates for the duration of the shortened impulse and selector magnet |53 remains released.

(3) When the peak portion 232-I of switchshifter E30-l 'leaves the indentation of cam 2ll5-l as stated above, it continues in engagement with the periphery of normal diameter of' cam M35-i, but peak portion 232-2 of switch-shifter 23S-2 which is in engagement with the periphery of normaI diameter of cam 2te-2 at the beginning of th'e third interval, reaches a point, say about live pei-"cent of the unit impulse length, beyond the beginning of the third'intervalwhere peak portion 232-2 engages they indentation of cam 2555-2 to close thecontact between Contact `uspring' member ZUB-2 and terminal 20d-2 during the. third interval. The contact so closed remains closed for 90 per cent'of the durationof the unit impulse lengtmwhereby the .second sel lecting impulse 'is also shortened for transmission over the circuit traceable from grounded positive battery 22%, conductorf 228, contact spring member litt-terminal 204,-2, conductor 223-2, .cons` tact spring member 2|8-2, mar terminal l erated the line relay 438, through the upper winding.

When .brush arm 434 begins to rotate and its brushes engage the start segments, 'a circuit closes from grounded positive battery the start segments interconnected by the brushes, conductor 448, spring No. 2 and its right-hand contact of switch fill, conductor 45?, through the upper winding of line relay 438, to point 458 of grounded negative potential furnished by batteries @5B and 45|. The direction of current through the upper winding of relaytS is from right to left and relay 338 operates, in response to the start pulse, to its spacing, or upper, position. rl"he spacing, or upper, Contact of relay 438 is connected to the winding of dummy magnet 452, but dummy magnet 452 does not operate at this time because its operating circuit is open, the circuit being traceable over a path extending from grounded negative battery 4&4, resistor 44'! of low resistance value, winding of dummy magnet 452, spacing contact and armature oi relay 438, spring No. 1 Vand its right-hand contact of switch 4H, conductor 436, and at this point the open condition exists inasmuch as the brushes of rotating arm 43d are passing over the start segments which are not included in the circuit.

When the brushes on rotating arm @itil reach the No. 1 segments of rings 401 and 598, the circuit including the upper winding of relay 538 is again closed and the direction of current therein is determined by the positions of the No. 1 transfer elements of transmitting Contact sets lill and 464, which positions are determined by the nature of the first selecting pulse of each of the signal combinations respectively passing over the transmitting contact sets 4B! and 554 at the time. The direction of the current flowing through the upper winding of relay 438 again determines the position to which the relay armature becomes operated, whereby a circuit is accordingly conditioned to operate either the selector magnet 4552 or dummy magnet 452. When the brushes on rotating arm 534 move out of engagement with the No. 1 segments of rings 401 and 58 and into enga-gement with segments Nos. 1A, the circuit including the upper winding of relay i313 is opened and the circuit previously conditioned is closed to operate either selector magnet 49.42 or dummy magnet 452, depending upon the position of the relay armature at the time. The magnet operating circuit is traceable from grounded positive battery 435, segments Nos. 1A of rings 4Q? and 58 interconnected by the rotating brushes, conductor 455, right-hand contact and spring No. l of switch 4i i, conductor 44| armature in engagement with either its marking, or lower, contact or its spacing, or upper, contact of relay 438, through the winding of the magnet connected to the conit was last operated by the current flowing through the upper Winding of the relay. Therefore, the lower winding of relay 43B serves to hold the relay in the position to which it was last operated and hold it in such position until the current in the upper winding flows in the opposite direction to that which operated the relay to its immediately previous position.

A clear understanding of the enciphering operation is had by referring to the signal VWave chart shown in Fig. 5. Fig. 5 shows lines a to o, which furnish the following information:

Line a shows the number of intervals, consecutively numbered, wherein different functions are performed by the rotating brushes moving over the corresponding segments of rings lill and 488 of the double distributor.

Line b shows the designation of the segments of each of rings 451 and 458 for transmitting a start-stop, five-unit permutation code signal combination. The brushes on rotatable arm 435 are tact so engaged, its associated resistor of low resistance value, to grounded negative battery 44,41. The current flowing in the circuit just traced also flows in the high resistance path parallel *o the circuit just traced which path extends through its associated resistor oi high normally in engagement with the rest segments. When the brushes start rotating they pass over, in turn, the start segments, segments No. 1 corresponding to the first selecting impulse of the signal combinations, segments 1A referred to herein as holding segments, segments No. 2 which correspond to the second selecting impulse, segments No. 2A Which are another pair of holding segments, segments No. 3 which correspond to the third selecting impulse, segments No. 3A which are still another pair of holding segments, segments'No. 4 which correspond to the four selecting impulse, segments No. 4A which are another pair of holding segments, segments No. 5 which correspond to the nfth selecting impulse, segments No. 5A which are another pair of holding segments and the stop segments to which the negative polarity of grounded negative battery 43S is applied for restoring relay @L38 to its marking position just before the brushes engage and come to rest on the rest segments.

Line c shows the polarities successively applied to the segments of ring 461 during the time the brushes are rotating through one revolution. Positive polarity from battery 435 is always applied to the rest segment, the start segment, and each of hold segments Nos. 1A, 2A, 3A, 4A and 5A. Positive polarity from grounded battery 455 or negative polarity from grounded battery 464 is successively applied to each of selecting segments Nos. 1, 2, 3, 4 and 5, depending on whether the mark, or lower, contact or the space, or upper, contact of transmitting contact set 4M is engaged by its respective transfer element of those designated Nos. 1 to 5. Negative polarity from battery 439 is always connected to the stop segment.

Line d shows the signal combination for the letter Z which represents a character of the key code. The start-stop combination for letter 2, including the start and the stop impulses consists of space, mark, space, space, space, mark and mark, the start and the stop impulses being space and mark, respectively, in accordance with the usual practice. l l Line e shows the signal combination for the letter 1, a letter of the plain text message. The start-stop combination for letter I consists of space, space, mark, mark, space, space and mark and in this case also the start and the stop impulses are always space and mark, respectively.

Line f shows the combination of impulses trans-l mitted to the upper winding of line relay- 438,-

2,564,621`AVY 17 these impulses being the resulting combination, or product, produced by combining each of the selecting impulses of letter Z with its corresponding one of the selecting impulses oi letter 1. In other words, the selecting impulses of a signal combination of the key code as applied by transmitting contact set 4M are superimposed, in turn, on their respectively corresponding selecting impulses of a signal combination of the plain text message as applied by transmittingV contact set 4D! for transmission over the operating circuit of relay 433, which circuit includes the upper winding of the relay. It will be noted as hereinbefore stated in the description of Fig. 3 that when a selecting impulse is combined with another impulse of like nature, the resultant is a mark but if the selecting impulse is cornbined with a selecting impulse of a different nature, the resultant will be a space These changes affect only the selecting impulses of a signal combination, but the start impulse and the stop impulse remain the same, that is "space and mar respectively.

Line y shows the nature and duration of each of the current impulses of line f as applied to the upper winding of line relay 438.

When the brushes on rotating arm 43d rotate through one revolution to transmit the signal combination shown in line f there are performed various functions which are indicated in lines h to o in Fig. 5. These functions are as follows:

(l) Normally the brushes on arm :i3d are in engagement with thc rest segments, and no current at this time ows in the upper winding of relay 438, as indicated in interval No. l of line g, because the relay operating circuit is open at the distributor segments.

ments, conductors est, right-hand contactand spring No. l of switch 4i I, conductor 134|, arrnature and marking contact of relay 1538, through the winding of selector magnet 442, resistor M3, to grounded negative battery dell, to furnish a current, as indicated in interval No. 1 of line It whereby selector magnet i132 is normally maintained in an operated condition. This current, at the same time flows through the parallel high resistance path extending through the lower Winding, in a right to left direction as indicated in interval No. 1 of line z, to normally hold relay 43S in its marking position as indicated by the two li/Fs shown in line i.

(2) In interval No. 2 when the brushes engage the start segments, positive polarity of grounded battery is applied to a circuit extending over the start segments, conductor e658, spring No. 2 and its right-hand contact of switch 4H, con*-V ductor dit?, through the upper winding, from right to left, of relay 35, to point t8 of negative potential furnished by batteries @5:3 and d5! to permit a spacing current indicated in line g, to operate the armature of relay 438 to its spacing position. as indicated by the two Ss shown in line h. l

(3) In interval No. 3 when the brushes engage the No. l segments to pick up the first selecting impulse or" each of the signal combinations for letters Z and 1, that is, mark at transmitting contact set der?, and space at trans--r mitting contact set fiiii, positive polarity of grounded battery 43555 is applied over the marking contact and transfer element No. i or transmitting contact set est, No. l segments of rings liti and litt, transfer ,element No. 1 in engage However, at this time there is closed a circuit traceable from the posiment with the spacing contact of transmittingcontact set lidi, conductor M8, spring member No. 2 and its right-hand contact of switch il l, conductor 467, through the upper winding, from right to left, of relay 438, to point lie of negative potential to transmit a space impulse as indicated in line g, and relay ett is therefore held in its spacing position as indicated in line h.

(4) In interval No. 4 when the brushes are inv engagement with the Nos. 1A segments, the current cwing through the upper winding, from right to left, of relay 438 drops to zero value as indicated in line g, and a space current now ows through a circuit traceable from grounded positive battery 435, segments Nos. 1A, conductor GSE, right-hand contact and spring No. l of switch di i, conductor Ml, armature and spacing contact of relay 438, through the winding of dummy magnet 452, as indicated in line Z, resistor 44'?, to grounded negative battery'lii to per-l mit a spacing current, as indicated in line z' to flow through the lower winding or" relay 43% for the duration of the interval No. 4 to hold the armature of relay i38 in its spacing position as indicated by the two Ss in line 7'.

(5) In interval No. 5 when the brushes are inengagement with the Nos. 2 segments a circuit is closed extending from grounded negative bat winding, from left to right, of relay 438, to point 468 which at this time is of positive potential, to furnish the second selecting impulse which is of spacing current as indicated in line g, to operate relay 438 to its spacing position as shown inline h.

(6) rIn interval No. 6 when the brushes come into engagement with segments No. 2A, a circuit is closed extending from grounded positive battery 1335, segments Nos. 2A, conductor 36, righthand contact and spring No. l of switch dii, conductor lidi, armature and spacing contact of relay 33, through the winding of dummy mag' net 452, resistor A41, to grounded negative battery G44, and the spacing current indicated in line l, operates dummy magnet $52 and flows from left to right through the lower winding of relay 638 as indicated in line i to maintain relay 438 in its spacing position as indicated in line y'.

(f1) In interval No. 7 the rotating brushes en-l gage segments No. 3 to close a circuit extending from grounded negative battery 464, spacing con# tact and transfer element No. 3 of transmitting contact set t', No. 3 segments, transfer element No. 3 and marking contact of transmitting contact set dei, conductor 165, spring No. 3 and its right-hand contact of switch 4i i, conductor 44S, through the upper winding, from left to right, of relay 38, to point it of positive potential, and the third selecting impulse which is also of spacing current as indicated in line g, retains the relay in its spacing position as indicated in line h.

(8) In interval No. 8 the brushes engage segments Nos. 3A to close a circuit from grounded positive battery 35, segments Nos. 3A, conductor G35, right-hand contact and spring No. 1T of switch fili, conductor dei, armature and spac-i ing contact of relay 438, through the winding oi dummy magnet 1352, resistor 4M, to grounded negativefbatteryiiand the spacing currentA indicatedin line l, operates dummyrnfignet|52 and iiows from left ,to rightthrough the lower Winding of relay |332 as indicated in line z' to retain the relay in its spacing position as indicated in line y'.

(9) In interval No. 9 the Yrotating brushes engage segments No. i to close a circuit extending' from grounded negativebattery 462i, spacing contact and transfer element No. e of transmitting contact set ,494, segments No. 4, transfer element No. tand spacing Contact ci transmitting contact set del, conductor riid'spring No. 2 and its right-hand contact of'switch 133|, conductor liti,

through the upper winding, from left `to right,.

of relay 38 to pointjiS of positive potential,

and the fourth seiecting impulse which is of' marking .current asindicated inline g operates magnet 442, the operating current for selector` magnet 442"` also `ilowing,,from right to left, through the lower Winding of relayj1i38 to vmaintain the relay in its marking Aposition as indicated inline y'. A Y

(11) In interval No. 11l the brushes engage segments No. 5 to close; a circuit extending from grounded postive'ba'ttery 455, marking contact and transfer element No. 5 of transmitting contact set 4M, segments No. 5, transfer element No. 5 and spacingcon'tact of transmitting contact set tei; conductor litt, spring No. 2 and right-hand contact of switch it i, conductor 461, through the upper winding, from right to left, of relay 638 to the point 458 of negative potential and the iiftli selecting'impulse is of spacing current as indicated in line g,l operates relay 38 toits spacing ,position as indicated inline h.

(l2) In interval No. 12 the `brushes engage segments Nos. 5A to close a circuit from groundedv positive battery '435, segments I\Tos.5A, conductor 436,righthand contact of spring' N011 of switch 4H, 'conductor 44|.,.the armature 'and spacing Contact ofV relay 413.8, throughV the winding'o'f' dummy inagnetliz, resistor lill?, to grounded negative battery 444, andthe spacing current operates dummy magnet 52, as indicated in line l, the operating current for dummy `magnet 552 also ilowing through ,the lower winding, from left to right, of relay 438 to maintain relay 438 in its spacing position as indicated vin line y'.

V.(13) In interval No. 13 the brushes engage the stop segments to close a circuit extending from grounded negative batteryathe stop segments, conductor 468, spring No.2 and `its right-hand contact of switch 4H, conductor 451', through the upper winding, from right to left, foi relay @38, to rpoint 468 of positive potential and the stop impulse vwhich .is always 'of Ymarking current as indicated in line g, operates relay i3d to its marking position as indicated [in line h.

v(14) Upon returning to interval No.' i vthe brushes again come to rest on the rest segments to, close a circuit traceable from :grounded positive battery 35, the rest segments, conductor 436, right-hand contactl and spring No, l of switch di conductor digarmature and marking contact of .relay .438, through the Winding-,of

sets |0| and |U4 are parts.

tain the relay inits marking position as indicated in line 7' until .another signal combination is received.

Byobserving the intervals wherein current isv flowing in either selector magnet 'i552 or dummy magnet -452 as indicated inlines Ic and l, it will' be noted that the operating'current 'has a dura-v tion of one .interval only so that each'of these magnets will release at the termination of each interval wherein the magnet is energized; It will be noted in lines m and n that 4a short,

sharp 'voltage pulse lis* radiated `each time either magnet operates or releases.` 'iherefore, at each possible transition of Ka signal wave corresponding to the signal combination indicated in line f, a

short, sharp voltage pulse is radiated which might' be picked up and recorded *by `a radio receiver and oscillograph located within range of the enciphering equipment shown in Fig. 1. Inline o is indicated the combined pick-upgat the radio receiver radiated bythe operating circuits of both magnets. The combined pick-up wave will be the same for all signal combinations whereby detection-of a secret message during A'the enciphering'operation ,is practically eliminated.

Deciphermg operation The deciphering operation is started-by inserting in unit |03 a perforated tape, -such'as tape |02, in which are perforatedrsignal combinations representative of an enciphered message. The

enciphered message perforated on tape |02, maybe similar to that resulting `from the enciphering operation vand recorded on reperforator it as just described under the caption of Enciphering operation. A key code tape, such as perforated tape |05, is inserted in yunit |66. Tapes |02 and |05 are drawn over the sensing pins of their respective transmitting contact sets |0| and H34 in a manner similar to that alsohereinbefore described. .Switch V|| is normally in its deciphering or left-hand, position.

When perforated tapes |02 and |05 are'in their proper places with respect to transmitting contacts |0| and |04 and switch is in its deciphering position, switch |32 is closedto con-` dition the distributor for operation and then tape stop switch ||4 is closed to start operating the 'transmitters whereof transmitting contact The tape sensing mechanism represented by transmitting contact set 0I of one transmitter and the transmitting contact set |04 of the other transmitter operate their respective sets of sensingiingers in accordance with the perforations, or control indicia,

in both the enciphered perforated tape 02 and the key code perforated tape |35 to control the simultaneous setting up of vimpulses symbolic e of two signal combinations as represented in the lower portion of Fig. 3. Simultaneous setting up of two signal combinations causes one signal combination to be superimposed on the other combination so that a different product, or signal combination, is produced. In this case, that is, in vthe decipherng operation, 4the resulting product should be the signal combination corresponding to a characterin the plaintext message as originally prepared 4and before being subjected to theenciphering operation.'

l For'a description of the operation of the circuits involved in deciphering messages, reference ls again made to Fig. 4. Switch is switch 4| in Fig. 4 and it will be noted in Fig. 4 that when switch 4| is in its deciphering position, periorator 4|0 is connected to the double transmitting distributor and therefore perforator 4|0 is now connected to receive the deciphered plain text message as the message was originally prepared.

As in the enciphering operation, hereinbefore described, the brushes on rotating arm 434 of the double distributor are normally positioned on the rest segments, the corresponding segments of the two rings |01 and |08 are xedly located in the same sector and are simultaneously contacted in turn, by the brushes on rotating arm 434 during each revolution. The start segments, selecting segments Nos. 1, 2, 3, 4 and 5 and the stop segments complete in turn, the operating circuit of line relay 431 whereby the opa erating current flows in the upper, or operating, winding of relay 431 in one or the other of two opposite directions depending upon the nature of the impulse resulting from combining an impulse of a signal combination received from transmitting contact set 404 and an impulse of another signaling combination received from transmitting contact set 40|. When the impulse` resulting in the output of the distributor is a space its direction of current is from right to left through the upper winding of relay 431 and when it is a mark its direction of current ls from left to right. The rest segments and hold segments Nos. lA, 2A, 3A, 4A and 5A, in turn, complete the operating circuit for either selector magnet 453 or dummy magnet 454, which circuit includes a high resistance locking, or holdlng, path extending through the lower winding of line relay 431, the current in the lower winding flowing in one or the other of opposite directions in accordance with the spacing or marking nature of the signal impulse which last operated the line relay 431 through its upper winding.

When brush arm 434 begins to rotate and its brushes engage the start segments, a circuit closes from grounded positive battery 435, the start segments interconnected by the brushes, conductor 448, spring No. 2 and its left-hand contact of switch 4| l, conductor 412, through the upper winding, from right to left, of line relay 431, to

point 469 of negative potential furnished by 'H batteries 413 and 414. The direction of current through the upper winding of relay 431 is from right to left, and relay 431 operates, in response to the start impulse, to its spacing, or upper,

position. The spacing, or upper, contact of relay 431 is connected to the winding of dummy mag. net 454, but dummy magnet 454 does not operate at this time because its operating circuit is open,

the operating circuit of dummy magnet 454 being ing over the start segments which are not in.

eluded in the operating circuit of magnet 454. When the brushes on rotating arm 434 reach the No. 1 segments of rings 401 and 408, the circuit including the upper winding of relay 431 is again Vclosed and the direction of current therein is determined by the positions of the No. 1 transfer elements vof transmitting contact sets 40| and 22 404 which positions are determined by the nature of the rst selecting pulse of each of the signal combinations respectively passing over the transmitting contacts 40| and 404 at the time. The direction of the current flowing through the upper winding of relay 431 again determines the position to which the relay armature is operated, whereby a circuit is accordingly conditioned to operate either the selector magnet 453 or dummy magnet 454. When the brushes on rotating arm 434 move out of engagement with the No. 1 segments of rings 401 and 408 and into engagement with segments Nos. 1A, the circuit including the upper winding of relay 431 is opened and the circuit previously conditioned is closed to operate either selector magnet 453 or dummy magnet 454 depending upon the position of the relay armature at the time. The magnet operating circuit is traceable from grounded positive battery 435, segments Nos. 1A of rings 401 and 408, conductors 433 and 456, armature in engagement with either its marking, or lower, contact, or its spacing, or upper, contact, of relay 431, through spring No. 4 or No. 5 of switch 4| I, through the winding of either magnet and its associated resistor of low resistance value, to grounded negative battery 460. Current owing in the circuit just traced also flows in a high resistance path parallel to the circuit just traced which path extends through the lower winding of relay 431, to grounded negative battery 460. Because of the high resistance values of the resistors adjacent to the lower winding of relay 431, current iiowing in the lower winding is very light but of suicient strength to maintain the armature of relay 431 in the position to which it was last operated by the current ilowing through the upper winding of the relay. Therefore the lower Winding of relay 431 serves to hold the relay in the position to which it was last operated and hold it in such position until the current in the upper winding flows in the opposite direction to that which operated the relay to such position.

A clearer understanding of the deciphering operation is had by referring to the signal chart shown in Fig. 6. Fig. 6 shows line a to o which furnish the following information:

Line a shows the number of intervals, consecutively numbered, wherein different functions are performed by the rotating brushes moving through one revolution over the segmentsl of each of rings 401 and 408 of the distributor.

Line b shows the designation of the segments of each of rings 401, 40B for transmitting a startstop, five unit permutation code signal combination. The brushes on rotatable arm 434 are normally in engagement with the rest segments. When the brushes start rotating they pass over, in turn, the start segments, segments No. 1 corresponding to the first selecting impulse of the signal combination, segments 1A referred to herein as holding segments, segments No. 2 which' correspond to the second selecting impulse, segments 2A which are another pair of holding segments, segments No. 3 which correspond to the third selecting impulse, segments No. 3A which are still another pair of holding segments, segments No. 4 which correspond to the fourth selecting impulse, segments No. 4A are another pair of holding segments, segments No. 5 which correspond to the fifth selecting impulse, segments Nos. 5A which are another pair of holding segments and the stop segments to which the negative polarity of grounded negative battery 438 is applied for restoring relay 431 to its marking position before' the brushes come torest on asentar the restsegmen'ts..The-positivefple of grounded positive battery "43.5 is connected to the rest sgments 'for normailyi'maintaining selector magnet @53 in its operated position.v

Line c Ysl'iows `polari'ties successivelyappliecl tothe segments of ring'itlll during the .time the brushes arezrotating through one revolution. The positive pole of batt'eryllil is always connected to 'the-rest segment, and in turn, when the brush arm'lill rotates through a revolution, tothe start segment and leach of the hold segments Nos. 1A, 2A, 3A,V 1lAland 5A. The positiyepole of battery F555, or the negative 'pole from battery' 'tot is successively connected'fto 'each ci selecting segment-3 Nos. l, 2, V'3, l and, vdepending on whether the mars, or loweiy'contact'or the space, or upper, Contact .is engaged by its "respective swinger 'of those designated Nos. 'l to 5 of transmitting contacts The 'negative pole Of'battery Lls is always connected to the stop segment.'

Line d shows the'signal combination for the letter Z which represents a character 'of the keycode. The startestopcombinaticn for letter 52? including the start and the stcpimnulse consistsof space, mark, space, space, snacerrnarl:

and mark, the start and the stop impulses being space'v and markfrespectively, in accordance with the usual practice.

Line e shows theenciphered signal which is a combination Vof impulses that is to be deciphered by means ci the'key code. Inother words, the selecting. impulses of a signal combination of a key code as 'applied by transmitting contacts 4M are'supe'rimposed, in turn, cntheir corresponding selecting impulses of asignal combination of the enciphered "message as" applied by transmitting "contacts 740|', for transmission over the operating circuit of' relay 33T 'which circuit includes the upper winding of the relay. It will be noted, as hereinbefore stated'in the description of Fig; 3,1that whenasel'ectingimpulse is ccmbined with another impulse 'of like nature, the resultant isa "marl but if the selecting' impulse is. combined with a selecting impulse of a different nature, theresultant' will 'be a space L.

However, these changes'aiiect only the selecting impulses of a'signal"'con'ibination, the "start impulsel and"the' stop impulse remain the same', that isfspace and 'mark respectively.

Line shows the deciphered ysignal combination aiswliich' are inicated in'lines 7i to o, These functions are as follows:

`(l) Normally the brushes 1534 are inA -ient with the'restsegments, no our*v indicated in'intervalflo. l of line because the relay operating circuit is 1open at the. distriiutor The armature ofwrelay 123'? is normally in its marking, or' lower, position 'as shown in inv terval No. 1 of line g''becaliSQ-Of .a holding current. normally o'wing, to left, 'through the' in line' e 'there 'are performed various:

in the upper windingof relay 43T, asl

245 lower win'cingbirelay'l in"'abatli' parallel' to a circuit extending fr'orr'itli'e'po'sitiye'beleef bat-' tery #335., the rest Segments', 'conductors' 536 'andi lii, armature and 'marking 'contact of relay F4311 left-hand Contact and spring No. 5 'of switch lil conductor el?, 'through' the" winding of selector" magnet 453, resistor'siil. of low resistance value, to grounded negative battery 559, to' furnishy a' marking current as indicated "in interval ING. 1' of line k, whereby selectorv magnet't is normally maintained in anope'rated condition.' i"l'ie"1arztl lel path extendingthrough'the lower winding, 'in a right to left diiec'tiofnfof relay 43? includesre' sistors 556i and E2 which are'of yhigh resist'aice' values, and resistor #353 which like resistor "1G59y is' of low resistance value, andthe ore, receives a 'small portion only of 'the current flowing" through the winding of' selector magnet 453', as' "idicated'in interValNo. 1 of'line v`2', which portion? isjust sumcientto'holdrelay' s3? in its marking position for the duration of interval No. v1 'as in,-AY

dica'ted by means'of thetwo Ms shown inline (2) .in .interval No. 2fwhen the brushes arez'iri" engagement with' the start segments, positive polarity of battery 435 is appliedIr toa 'circuit'exi-J tending over the 'start segments, conductor '458, spring No. 2 and its left-hand contact cf'switch 43H, conductor M2, throughr'the'uppe'r'j winding,` from right to left, or relay 31, topoint -ll'' of negative potential furnished by batteries ,573 and im to permit a spacingcurrent indicated in lin' 9', to operate relay 43T toits spacingpos'ition as',y indicated by means of fthetv'JoY Ss shown iri line h. No currentr flows in thelower winding oiy relay '53? as shown inline'i. l y

(3) in interval No. 3jwhen' the brushes are' in' engagement with the No. l segments to'piok up the first selecting impulse of eacli'cfuthe 'signal combinations appearing at each sett' ci' transf mitting contacts, that' is, Aniarlg attr'ans'niitt'in'g Contact set 5M and space at transmitting 'con-l' tact set il, positive polarity'ofbattery l is applied over the marking Contact and transfer element No. 1 of transmitting Contact set t, the No. i segments, transfer element No. `1 in er1-- gagement with the spacing contact of transmit-` ting contact setillrjconductor M3,V spring No. 2 and its left-hand Contact of switch riti, conductor 472, through the upper Winding'ofre'lay 43?, in a right to left direction,v to point 469 o F negative potential to transmit a space impulse indicated inline g, and relay 437 is held in its spacing posi-` tion as indicated bythe two Ss shown in line h; No current lowsat this time in the lower Winding as shown inline i. l Y

(Il) Ininterval Noewhen the brushes areinengagement with the iNos. '1A segments, 'the cur' rentiiowing through lthe upper winding, righttoj le'ftgof relay 431, returns to zero 4value as indicated in line g and aspace current now flows through ,the circuit Itraceable from groundedy pos# itive battery 435, segments Nos. 1A, conductorsl 438 and B5B, armature andv spacing contact of' relay ydel, conductor :275, left-hand contact and z spring No. 4 of switch il l conductor 476, through the winding of dummy magnet 4751i, fas indicated y as indicate'd in line' wl'iichhol'dsrelay 31 in its 25 spacing position for the duration of interval No. 4 as indicated by the two Ss in line y'.

(5) In interval No. 5 when the brushes are in engagement with the Nos. 2 segments, a, circuit is closed extending from grounded negative battery 464, spacing contact and transfer element No. 2 of transmitting contact set 40|, segments No. 2, transfer element No. 2 and spacing contact of transmitting contact set 40|, conductor 448, spring No. 2 at its left-hand contact of switch 4| conductor 412, through the upper winding, from right to left, of relay 431, to point 469 which is now of positive potential to furnish marking current for the second selecting impulse, as indicated in line g to operate relay 431 to its marking position as indicated in line h. No current flows at this time in the lower winding of relay 431 as indicated in line (6) In interval No. 6 when the brushes come into engagement with segments Nos. 2A the current owing through the upper winding from right to left, of relay 431 drops to zero value as indioated in line g, and marking current now flows through acircuit extending from grounded positive battery 435, segments Nos. 2A, conductors 436 and 456, armature and marking contacts of relay 431, conductor 451, left-hand contacts of spring No. 5 of switch 4| conductor 411, through the winding of selector magnet 453, indicated in line lc, resistor 459 of low resistance value, to grounded negative battery 465 and magnet 453 operates. The operating current for selecting magnet`453, also follows the parallel path traceable through resistor 46 through the lower winding of relay 431, resistors 462 and 463 to grounded negative battery 460. The current ilowing at this time in the lower winding of relay 431 is in a right to left direction, or marking, as indicated in line i, to hold relay 431 in its marking position for the duration of interval No. 6 as indicated in line i.

('1) In interval No. '7 when the brushes come into engagement with segments Nos. 3, a circuit is closed extending from grounded negative battery 464, spacing contact and transfer element No. 3 of transmitting contact set 404, segments Nos. 3, transfer element No. 3 and spacing contact of transmitting contact set 40|, conductor 448, left-hand contactsy of spring No. 2 of switch 4|l, conductor 412, through the upper winding, from left to right, of relay 431 to point 469 which remains at positive potential to furnish marking current for the third selecting impulse as indicated in line g, and relay 431 remains in its marking position as indicated in line h. No current ows in the lower winding of relay 431 as indicated in line i.

(8) In interval No. 8 when the brushes come into engagement with segments Nos. 2A the current owing through the upper Winding from left to right, of relay 431 again drops to zero value as indicated in line g, and marking current now iiows in a circuit extending from grounded positive battery 435, segments Nos. 3A, conductors 436 and 456, armature and marking contact of relay 431, conductor 451, left-hand contact and spring No. 5 of switch 4| conductor 411, through the winding of selector magnet 453,Y resistor 459, to grounded nega-tive battery 460 and the current as indicated in line 1c operates selector magnet 453. At the same time the operating current for selector magnet 453 also ows through the parallel path including resistor 46|, lower winding, from right to left, of relay 431, resistors 462 and 463, grounded negative battery 460, the current as indcd inline irQWillS in; the lower winding,

26 from right to left, serving to hold relay 431 in a marking position for the duration of interval No. 8 as indicated in line fi.

(9) In interval No. 9 when the brushes come into engagement with segments No. 4, a circuit is closed extending from grounded negative battery 464, spacing contact and transfer element No. 4 of transmitting contact set 404, segments No. 4, transfer element No. 4 and marking contact of transmitting contact set 40|, conductor 466, -spring No. 3 at its left-hand contact of switch 4| conductor 419, through the upper winding, from right to left, of relay 431, to the point 469 which is still of positive potential to furnish at this time a, spacing current representing the fourth select- -ing impulse as indicated in line g, and serving to operate relaye? at this time to its spacing position as indicated in line h. No current flows in the lower winding of relay 431 as indicated in line z'.

(10) In interval N o. l0 when the brushes come into engagement with segments Nos. 4A, the current flowing through the upper winding, from right to left, of relay 431 returns to Zero value as indicated in line y and spacing current now ows, a circuit extending from grounded positive battery 435, segments Nos. 4A, conductors 435 and 456, armature and spacing contact of relay 431, conductor 415, left-hand contact and spring No. 4 of switch 4| i, conductor 416, through the winding of dummy magnet454, resistor 463, to grounded negative battery 460. The spacing current indicated in line l, operates dummy magnet 454. At the same time the operating current for dummy magnet 454 also flows through the parallel path traceable through resistor 462, through the lower winding, from left to right, of relay spacing 431, resistors 46| and 459,to grounded negative battery 460, as indicated in line i. The current Howing through the lower winding, from left to right, of relay 431 serves to hold the relay in its spacing position for the duration of interval No. l0 as indicated in line 7.

(11) In interval No. l1 when the brushes come into engagement with segments No. 5 a circuit is closed extending from grounded positive battery 465, marking contact and transfer element No. 5 of transmitting contact set 404, segments No. 5, transfer element No. 4 and spacing con-` tact of transmitting contact set 40|, conductor 448, spring No. 2 and left-hand contact of switch 4||, conductor 448, spring No. 2 and left-hand contact of switch 4| conductor 412, through the upper winding, from right to left, of relay 431 to point 469 of negative potential to furnish at this time a, spacing current representing the fth selecting impulse Vas indicated in line g and relay 431 therefore remains in its spacing position for the duration of interval No. 11 as indicated in line h.

(l2) In interval No. 12 when the brushes come into engagement with segments No. 5A the current flowing through the upper winding, from right to left, of relay 431 returns to zero value as indicated in line g and spacing current now flows in a circuit which is closed from grounded positive battery 435, segments No. 5A, conductors 456 and 436, armature and spacing contact of relay 431, conductor 415, left-hand contact and spring No. 4 of switch 4H, conductor 416, through the winding of dummy magnet 414, resistor 463, to grounded negative battery 460 and the spacing current as indicated in line Z, operates dummy magnet 454 for the duration of in'- terval No. 12l` The operating current for dummyof the selected one of said recording sets arranged to follow the polar characteristic of said single signal, segmented means controlled by said rotatable means for holding the polar relay of said selected one of said recording sets and either of said magnets operated thereby in operated positions for a predetermined interval after each impulse of said single signal combination has been received and for releasing the operated magnet at the end of said predetermined interval, means controlled by one magnet of each of said recording sets for recording signals received from said distributing means, an operating circuit for each of said magnets of each of said recording sets for radiating a voltage impulse at every possible transition in the signal wave of said single signal received from said distributing means.

4. A device for use with secret telegraph systems comprising transmitting sets for sending permutative code signals of mark and space impulses, recording sets, each of said recording sets including a polar relay, a work circuit and a dummy circuit having electrical characteristics identical therewith controlled by said relay, a magnet controlled by each of said circuits, distributing means, switching means for selecting, as desired, any one of said recording sets for oonnection to said distributing means, an operable element for starting said transmitting sets and said distributing means simultaneously, rotatable means in said distributing means controlled hy said operable means for combining the signals simultaneously received from said transmitting sets to produce a single signal of mark and space impulses, a circuit including a winding of the polar relay of the selected one of said recording sets for causing the polar relay to follow the mark and the space characteristic of said single signal, a second circuit prepared by the polar relay in its mark position for operating the magnet in the work circuit and in its space position for operating the magnet in its dummy circuit and closed momentarily under control of said rotatable means after each impulse of said single signal is received in the first-mentioned circuit, a parallel path in said second circuit for maintaining the polar relay in its last operated position until the next impulse of said single signal is received in the first-mentioned circuit, said second circuit of each recording set having means arranged to operate one magnet for the marking impulses and the other magnet for the space impulses in non-overlapping time relation for successive pulses whereby the patterns of energy radiated from any of said recording sets for like number of pulses in any of said single signal combinations of mark and space impulses are identical.

5. In a telegraph system, a tape sensing mechanism, a signal responsive relay having an armature engageable with either of two contacts, a signal responsive recorder operable through one of said contacts, and a distributor having spaced segments for controlling said relay according to said tape sensing mechanism and having other segments individually disposed between each two of said first-mentioned segments for applying to said armature an operating potential for said recorder.

6. In a cipher telegraph system, a tape sensing mechanism for sensing tape containing a message sequence of code combinations, a. tape sensing mechanism for sensing a tape containing a key code sequence of code combinations, a distributor having means for intercombining code combina- -tions sensed'by said two tape sensing mechanisms, -an electromagnetic work element having an operating circuit, an electromagnetic dummy element having an operating circuit, a signal relay responsive to a signal product of an intercombination.

of code combinations simultaneously sensed by said mechanisms to prepare one or the other ofv said circuits for operation in accordance with said intercombined signals, and means in said distributor for completing the prepared one of said circuits.

7. In a cipher telegraph system, a tape sensingl mechanism for sensing a tape containing a message sequence of code combinations, a tape sensing mechanism for sensing a tape containing. a key. code sequence of code combinations, a distributor having individual to each of said tape sensing mechanisms a segmented ring, said rings containing code segments connected to said tape sensing mechanisms and other segments alternating with said code segments, two transmission paths in a circuit including said other segments alternating with said code segments, a relay controlled through the code segments of said distributor and having an armature adapted to prepare either of said two signal transmission paths, and means including said other segments for completing the prepared one of said paths.

S. In a cipher system, a distributor having two segmented rings, a tape sensing mechanism adapted to sense either a plain text message tape or an enciphered message tape and arranged to selectively connect either of two polarities to certain segments of one of said rings, a polar signal responsive relay having two operating paths and two holding paths, another tape sensing mechanism adapted to sense a key code tape and arranged to selectively connect the corresponding segments of the other of said rings to either of said polar relay operating paths, and means in said distributor for interconnecting the correspending certain segments of said two rings in succession whereby to intercombine signal characteristics by said two sensing mechanisms and operate said relay in accordance therewith, and for interconnecting the other of said segments of each of said rings in succession for applying a potential to either of said holding paths to thereby hold said relay in its last operated position until one or the other of said operating paths is again closed by said interconnecting means engaging the next succeeding pair of said corresponding certain segments of said rings.

9. In a cipher telegraph system, a tape sensing mechanism for sensing tape containing a message sequence of code combinations, a tape sensing mechanism for sensing a tape containing a key code sequence of code combinations, a distributor having means for intercombining code combinations sensed by said two tape mechanisms, a signal responsive relay having an armature engageable with either of two contacts, a signal responsive recorder operable through one of said contacts, two segmented rings included in said distributor, each having spaced segments for controlling said relay according to each code combination resulting from the intercombining of said message and said key code combinations and having other segments individually disposed between each of said spaced segments on its ring for applying to said armature an operating potential for said recorder.

10. In a cipher telegraph system, a signal receiver, a tape sensing mechanism for sensing a 

